Process for sealing containers



Oct. 30, 1962 G. E. ECKMAN PROCESS FOR SEALING CONTAINERS 2 Sheets-Sheet 1 Original Filed Nov' 50, 1956 IN1/Enron 650/365 E. F6/(MAN 3%.. wf

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Oct. 30, 1962 G. E. ECKMAN PROCESS FOR SEALING CONTAINERS Original Filed Nov. 50, 1956 2 Sheets-Sheet 2 INVENTOR.

United States Patent Oiiice 3,060,652 Patented Oct. 30, 1962 3,060,652 PROCESS FOR SEALING CONTAINERS George E. Eckman, Oradell, NJ., assignor to American Can Company, New York, N.Y., a corporation of New Jersey `Original application Nov. 30, 1956, Ser. No. 625,511, now Patent No. 2,923,453, dated Feb. 2, 1960. Divided and this application Api'. 16, 1959, Ser. No. 306,927

4 Claims. (Cl. 53-22) This invention relates to containers for frozen foods and more particular to an improved process for sealing the same.

To meet the demands of the frozen food industry it is required to provide an inexpensive liquid tight fibre container which, when empty, may be nested for transportation and storage without wasting space; and which, after filling, is scalable in a manner that iwill prevent liquid leakage.

In addition, provision must be made for the expansion of the contents during the freezing operation. The expansion room, known as head space, is the space between the fill line of the container and the cover. The problem with the head space is that, if it contains air, freezer burn may result; e.g. the air dries up the food which detracts from the sala-bility of the goods. It follows that industry demands a container having a head space as free of air as possible. Admittedly, vacuum packing would solve this problem, but vacuum packing necessitates the use of expensive, cumbersome equipment. Applicant has solved this problem by providing an improved fibre food container which by its inherent structure facilitates expelling enough air from the head space during the sealing operation to satisfy the demands of the frozen food industry. This container is covered by United States application Serial No. 625,511, filed November 30, 1956, now Patent No. 2,923,453, entitled Container and Process for Sealing the Same. The present application is a division of this parent application, and is directed to the method of sealing this improved container.

It is thus an object of this invention to provide an improved method for sealing a fibre food container.

It is a further object of this invention to provide an improved method of interlocking an upwardly extending .cover flange and a downwardly extending body flange on a fibre container, which has previously been filled with a product, to provide an improved end seam.

Another object of the invention is to provide a method of sealing the body and cover flanges of a fibre container by utilizing the inherent resiliency `of these parts to effect their mutual interengagement.

It is a still further object of this invention to provide an improved process for sealing containers wherein the container is partially evacuated during the sealing process.

Numerous other objects and advantages yof the invention will be apparent as it is lbetter understood yfrom the following description, which, taken in connection with the accompanying drawings, discloses a preferred ein bodiment thereof. v Briefly this invention relates to a process of forming an end seam in a filled food container provided with vertically inclined body and cover sealing flanges wherein the cover is first inserted into the container body in order to interlock the sealing flanges, and this insertion of the cover acts to expel air from the container head space to partially evacuate the container. The sealing process is completed by withdrawing the cover until the complementary flange portions are interlocked and then heat sealed.

Referring to the drawings:

FIGURE 1 is a perspective view of a container sealed by the process of the instant invention;

FIG. 2 is an enlarged sectional view of the .container taken substantially through plane 2-2 of FIG. l, in the direction of the arrows and a side elevation, partially 1n section of some -of the elements including a chuck and a mold used in the sealing process;

FIG. 3 is an enlarged fragmentary sectional view of the container sealing construction taken substantially along plane 3-3 of FIG. 1, in a direction of the arrows;

FIG. 4 is an enlarged fragmentary sectional View of a container opening tab taken `substantially along plane 4 4 `of FIG. 1, in the direction of the arrows:

FIG. 5 is an enlarged exploded view, partially in section, showing `a portion of the elements of the container yand the sealing `apparatus 'before the container body has been covered;

FIG. 6 is another fragmental View of the elements of FIG. 5 with the cover shown in a pre-assembly position relative to the container body;

FIG. 7 is a view similar to FIG. 6 showing the cooperation of the elements just after the actual sealing operation; and

FIG. 8 is a reduced scale view, partially in section and shows the covering chuck acting to remove the sealed container from the mold.

As a preferred or exemplary embodiment of the invention, the drawings show a method of forming a top end seam in a filled container which comprises a body 12 and a cover 14, (FIG. l). The body 12 is a dishshaped paper or fibre container of any selected contour having upwardly and outwardly extending walls to allow for nesting vof empty containers thereby saving space during shipment and storage. The container body 12 preferably is lined with any well known coating agent, such as parafiin or thermoplastic material to provide a liquid tight lining. The body 12 is provided further with a surrounding peripheral hem 16 which, in cross-section, is in the form of an inverted U, and which for purposes of definition shall be called caret shaped. The caret shaped hem has one leg 13 (FIGS. 3 and 5), which actually is `a continuation of the wall of the body portion and an inner, or inturned leg or flange 15, which is bent inwardly and downwardly to form a peripheral termination lying substantially in the plane of the fill line 17 of the container (FIGS. 2 and 3). The upper peripheral edge 19 of the hem lies substantially in the plane of the cover 14 (of the `sealed container) (FIGS. 2 and 3) and, therefore, the hem 16 may be described as having a vertical component substantially equal to the head space 21 (FIGS. 2 and 3) of the container. The space 23 (FIGS. 3 and 5) between the legs of the hem 16 before the sealing operation, is slightly greater than the thickness of the cover material (later described) so as to provide for clearance during the interfitting of the flanges of the cover and the container body.

Cover 14 like body 12 is made of coated fibre or paper, and it is substantially planar and 4o-f the same general contour as that of the upper periphery of the body portion 12 with free dimensions slightly greater than those of the inner peripheral termination of hem 16. The cover 14 is provided further with a peripherally depending channel 18 which in cross-section (as shown in FIGS. 3 and 5) has a V-shape; with the outer leg or flange 25 of the V being substantially equal in length to the inner leg or flange 15 of the caret shaped hem 16. In a preferred form, the outer leg of the V-shaped cover channel 1S, has a vertical component substantially equal to that of hem 16 and to that of the head space 21 of the sealed container and it follows that the interlocking portions of the hem 16 and V-shaped channel 1S can be called coniplementary.

With this construction, it is apparent that the cover 14 must be pressed down into the container, through the .9 head space, before the corresponding legs or flanges of the hem 16 and channel 1S are positioned to be interlocked (see FIG. 6). This position of the parts may be reached in spite of the fact that the cover is larger than the inner periphery of hem 16, since the body and cover of the container are formed of coated paper or fibre having a natural resiliency. Therefore, the corresponding legs or flanges of the hem and channel are defiectecl as the cover is inserted into the container body thereby permitting the cover to be inserted into the container body to the FIG. 6 position. Parenthetically, it should be noted that the inner surface of the hem 16 and the surface of leg 25 of the V-channel 18 are coated with a suitable heat sealing material such as a modified polyethylene, whereby the interlocking elements may be sealed together by the application of heat.

While the cover is being moved down into the container body, towards its FIG. 6 position, any air in the head space 21 will be compressed and forced out of the container about the peripheral edge of the outer leg 25, of the V-shaped channel 13; e.g. the greater air Messure (within the container) will act to radially compress the outer leg 25 of the channel 18 to permit the compressed air within the container to escape. Furthermore, during that instant when the outer leg 25 of the V-shaped channel has just passed the edge of the inner leg 15 of the hem 16while the outer leg 25 of the channel is being urged, resiliently, into peripheral contact with the body 12--a peripheral air gap 27 (FIG. 6) is provided permitting air to escape from the container. Gn the other hand, when the cover 14 is withdrawn to move the outer leg 25 of the V-shaped channel into its FIG. 3 position, the greater air pressure (atmospheric pressure outside the container) will add to the inherent resiliency of the leg 25 urging it into closer contact with the wall of the container thereby providing an effective air seal that prevents air from leaking back into the container. The amount of air thus expelled during the covering operation creates a partial vacuum in the head space, thereby meeting the demands of industry.

In order to provide for the opening of such a sealed container, the cover 14 is equipped with a tab 29 (FIGS. 1 and 4) which is an integral continuation of a portion of the outer flange or leg 25 of the V-shaped channel With this construction, when the tab 29 is gripped in the fingers and pulled into the plane of the cov the latter will be peeled out of the hem 16 at one end of the container and may then be removed from the container.

In view of the fact that filling and sealing machinery is well known in the art, the following description is intended to `show the method steps of the instant invention, rather than the details of the equipment which would be used in carrying out these steps.

In this light, an empty container 12 is positioned in a mold 3i) which has a cavity 32 corresponding to the shape of the body 12 of the container. The container is then filled with the food product up to a fill line 17 (FIG. 2) which has been selected to leave a required head space in a covered container. Then a sealing chuck 34 which has a face shaped to correspond `substantially to the upper contour of the cover 14 grips the cover 14 from a stack or other storage device (not shown)-the cover 14 being held in contact with the face 36 of the chuck by vacuum means which is provided by connecting a number of interconnected vacuum passageways or ports 38 extending frorn the face of the chuck 34 to a vacuum line 40, as shown in FIG. 2.

The chuck 34 is then guided by suitable machinery (not shown) from the position shown in FIG. 5 to the position shown in FIG. 6. In this travel, as described above, the outer leg or flange 25 of the V-shaped channel 18 engages the inner leg 15 of the caret shaped hem 16 with the corresponding parts compressing one another as the cover is moved relative to the container body towards the FIG. 6 position. When the position illustrated by FIG. 6 is reached the outer flange or leg 25 of the V-shaped channel 18 springs outwardly into peripheral engagement with the inner wall of the body 12. During this movement of the outer leg 25 of the V-shaped channel 13, the air gap 27 exists permitting compressed air to escape from the container. It will be noted that the chuck 34 is under-cut or notched at 35 to prevent the chuck from blocking the air escape.

Since the cover 14 is still held by the vacuum chuck 34, the cover is then withdrawn to the position shown in FIG. 7 where the outer leg 25 of the V-shaped channel interlocks with the inner leg 15 of the caret shaped hem 16. During this movement from the FIGURE 6 to the FIGURE 7 position, the interengagement of the cover outer leg 25 with the peripheral wall of the body 12 acts as a seal to prevent air from leaking back into the head space and accordingly a partial vacuum is created within the container.

When the elements are in the FIGURE 7 position, a plurality of sealing jaws 42 which are equipped with heating elements 44 (FIG. 2) are moved laterally into engagement with the hem of the container body 12. It will be noted here that because of the face 36 of the chuck 34 corresponds to a contour of the cover 14 in its sealed position, the peripherally inclined surface 46 (FIGS. 2 and 5) of chuck 34 acts as a back stop during the sealing operation; that is it butts up against the hem 16 and holds it firmly while the heated sealing jaws are brought into contact with the hem 16.

Since the inter-engaged parts of the cover 14 and the body hem 16 have been coated with a suitable heat sealing material (as heretofore described), the contact of the heated sealing jaws with the hem produces an air and liquid tight seal between the cover 14 and the container body 12 at the hem 16.

After the sealing operation, the chuck 34 still vacuum connected to the cover 14, is then raised to lift the filled container out of the mold 30 thereby making room for the insertion of another empty container. The filled container stays attached to the chuck 34 until the vacuum in line 40 is released.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the steps of the process described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the process hereinbefore described being merely a preferred embodiment thereof.

I claim:

l. The method of covering and expelling air from the head space of a filled container having a peripherally extending inturned caret shaped channel on its body portion and an interlockable radially disposed flange on its interfitting cover with the interlockable portion being coated with a thermoplastic material comprising the steps of filling said container to a level below said inturned channel within the container body, gripping a central portion of the outer surface of said cover, inserting said cover through said grip thereon into said container until said channel and flange pass one another to expel air from the container head space, withdrawing said cover through said grip thereon and increasing said head space until said channel and flange are interlocked in a loosely formed seam, and, While said cover is still retained by said grip, applying heat and pressure to opposite sides of said loose seam to press the seam layers together and thus cause the thermoplastic material in the seam to unite the layers in a strong and effective bond.

2. The process of forming a top end seam in a container having a peripherally extending inturned caretshaped channel on its body portion interlockable with a peripherally depending V-shaped channel on its internal cover of resilient material, and having the outer peripheral dimensions of said V-shaped channel radially expandable to the inner wall `of said body portion, said process comprising the steps of positioning said cover on a chuck shaped to correspond to the upper outer surface of said cover while having outer dimensions substantially equal to and shaped to conform with a predetermined inner dimension of said V-shaped channel thereby permitting controlled resilient radial movement of the outer leg of said V-shaped channel, gripping a central portion of said cover against said chuck, inserting said gripped cover by means of said chuck into said body portion until the corresponding legs of said V-shaped channel and said caret-shaped channel pass one another to permit said outer leg of the V-shaped channel to expand radially outwardly into engagement with the inner wall of said body portion, withdrawing said gripped cover by means of said chuck until said corresponding legs are in interlocking juxtaposition, and sealing said interlocked seam elements by pressing the same with a heated iron against the periphery of said chuck while said cover is gripped thereby.

3. The process of forming a top end seam in a container having a peripherally extending inturned caretshaped channel on its body portion interlockable with a peripherally depending V-shaped channel on its internal cover of resilient material, and having the outer peripheral dimensions of said V-shaped channel radially expandable to the inner wall of said body portion, said process comprising the steps of positioning said cover on a vacuum chuck shaped to correspond to the upper outer surface of said cover while having outer dimensions sub` stantially equal to and shaped to conform with a predetermined inner dimension of said V-shaped channel thereby permitting controlled resilient radial movement of the outer leg of said V-shaped channel, vacuum gripping a central portion of said cover against said vacuum chuck, inserting said gripped cover by means of said vacuum chuck into said body portion until the corresponding legs of said V-shaped channel and said caret-shaped channel pass one another to permit said outer leg of the V-shaped channel to expand radially outwardly into engagement with the inner wall of said body portion, withdrawing said gripped cover by means of said vacuum chuck until said corresponding legs are in interlocking juxtaposition, uniting said interlocked elements in an end seam, lifting the closed container from its position by means of said vacuum chuck and then freeing said container at a predetermined time by releasing the vacuum in said chuck.

4. The process of forming a top end seam in a container having a peripherally extending inturned caretshaped channel on its body portion interlockable with a peripherally depending V-shaped channel on its internal cover of resilient material and having the outer peripheral dimensions lof said V-shaped channel radially expandable to the inner wall of said body portion, said process cornprising the steps of positioning said cover on a chuck shaped to correspond to the upper outer surface of said cover while having outer dimensions substantially equal to and shaped to conform with a predetermined inner dimension of said V-shaped channel thereby permitting control-led resilient radial movement of the outer leg of said V-shaped channel, gripping a central portion of said cover against said chuck, confining a container body in a mold in alignment with said chuck and the cover gripped thereby, inserting said gripped cover by means of said chuck into said body portion until the corresponding legs of said V-shaped channel and said caretshaped channel pass one another to permit said outer leg of the V-shaped channel to expand radially outwardly -into engagement with the inner wall of said body portion, withdrawing said gripped cover by means of said chuck until said corresponding legs are in interlocking juxtaposition, and uniting said interlocked elements to fonn an end seam.

References Cited in the tile of this patent UNITED STATES PATENTS 927,801 Jenkins July 13, 1909 1,085,557 Everett Jan. 27, 1914 1,641,743 Dawson Sept. 6, 1927 2,713,423 Russell July 19, 1955 2,729,377 ONeil Jan. 3, 1956 2,825,194 Page Mar. 4, 1958 2,894,361 Ullman et al. July 14, 1959 2,942,390 Lerner June 28, 1960 

